The
mudpuppy (Necturus maculosus) and lesser siren (Siren intermedia)
spend their entire lives in water and never lose the gills, tail fins,
and gill slits that they developed as larvae.

Eight
species of Illinois salamanders (family Plethodontidae) have no lungs
and breathe mostly through the skin and lining of the mouth.

A
constriction ring at the base of the four-toed salamander's (Hemidactylium
scutatum) tail allows this animal to detach the tail and distract
a potential predator.

The
smallest Illinois salamander is the four-toed salamander (Hemidactylium
scutatum) at a length of four inches (10 cm). The largest Illinois
salamanders are the hellbender (Cryptobranchus alleganiensis) and
lesser siren (Siren intermedia), each
of which may attain a length of 18 inches (46 cm).

The
female zigzag salamander (Plethodon dorsalis) guards her eggs for
up to three months as the embryos develop. She usually does not eat anything
during this time.

There
are no male silvery salamanders (Ambystoma platineum). The females
are triploid,
having three sets of chromosomes per cell instead of the usual two sets.
This species is the result of a hybridization between the Jefferson (Ambystoma
jeffersonianum)
and blue-spotted (Ambystoma laterale) salamanders.

The
skin of the eastern newt (Notophthalmus viridescens) contains powerful
chemicals, including tetrodotoxin,
that deter predators.

When
disturbed, the redback salamander (Plethodon cinereus) displays
a defensive behavior in which it remains immobile, then curls into a tight
coil with its head under its upraised tail.

If
its pond or stream dries up, the lesser siren (Siren intermedia)
burrows deeply into bottom sediments, secretes a mucous
"cocoon" around itself, and aestivates for several months until
the pond fills again.